Loans - Additional Information (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2020 USD ($) loan	Mar. 31, 2019 USD ($) loan	Dec. 31, 2019 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net unamortized loan fees	$ 3,267,000		$ 3,092,000
Percentage of comprised loan, commercial, industrial and agricultural loans	38.00%		37.00%
Percentage of comprised loan, commercial mortgage loans	30.00%		29.00%
Percentage of loan-to-value to business equipment	80.00%
Percentage of loan-to-value to accounts receivable	70.00%
Percentage of loan-to-value to business inventory	60.00%
Percentage of loan-to-value to real estate	85.00%
Percentage of residential real estate loan in portfolio	29.00%		29.00%
Minimum period to be considered for loan to have defaulted	90 days		90 days
Loans modified as troubled debt restructuring with subsequent defaults | loan	0	0
Principal balances forgiven in connection with loan restructuring	$ 0		$ 0
Number of loans, period of time | loan	0	0
Modified in a troubled debt restructuring	$ 9,597,000		$ 9,802,000
Financing receivable, allowance for credit losses, w-downs	$ 910,000	$ 818,000
Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Maximum percentage of consumer loan and credit card in portfolio	4.00%		4.00%